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Unification of token confirmation and contract invocation in Ethers.js
When interacting with decentralized applications (dApps) created on the basis of Ethereum, a common model is the transfer of tokens to a smart contract. However, this can lead to unnecessary overhead and potential security risks, as it requires two separate calls: the proxy check and the contract call.
In the current implementation, we make two separate calls:
waiting for token.approve(contractAddress, amount);– Approval of a certain amount of tokens for a specific contract.
waits for contract.myFunction();— call of the contract function using verified tokens.
This approach can be cumbersome and error-prone because it requires manual control of the approval process and ensures that only certain functions are used in the contract.
Introducing Single Call: Token Validation and Contract Call in Ethers.js
To simplify this process and reduce unnecessary overhead, we introduce a new method called “approveAndInvoke”. This function will combine the token verification with the contract call into a single call.
import {airs} from 'airs';
/**
* Combines token verification and contract call into one call.
*
* @param {string} tokenAddress — the address of the token to be checked.
* @param {string} contractAddress — the address of the smart contract that will be invoked.
* @param {number} amount — the amount of tokens that must be confirmed for the contract.
*/
asynchronous function approvedAndInvoke(tokenAddress, contractAddress, amount) {
// Get an instance of the supplier
const provider = await ethers.getProvider();
// Check the token for this contract
const approvedResponse = wait for supplier approval (tokenAddress, contractAddress, amount);
if (!approveResponse) throw new Error ('Token approval failed');
// Call the contract function using verified tokens
ask {
await provider.invokeStatic(contractAddress, 'myFunction', { tokens: [amount] });
} catch (error) {
console.error(error); // Verification and retrieval of the token failed
}
}
default export approvedAndInvoke;
Usage example
import {approveAndInvoke} from './approveAndInvoke';
// Replace with token address, contract address and amount
const tokenAddress = '0x...'; // Replace with actual token address
const contractAddress = '0x...'; // Replace with actual contract address
constant sum = 10n;
confirm and call (address of token, address of contract, amount). then (() => {
console.log('Token verified and successfully invoked!');
}).catch((error) => {
console.error(error); // Verification and retrieval of the token failed
});
This “approveAndInvoke” function takes the required parameters, validates the specified tokens for the given contract, and invokes the contract function using these validated tokens. This approach reduces the costs of manually checking authorization and calling the contract, which makes it a more convenient and secure way to interact with Ethereum-based dApps.
